Allergen Triggers and Asthma: What you Need to Know

Managing Your Asthma: Avoiding Allergens

Triggers are things that can irritate the airways or cause reactions in people who are sensitised (allergic). There are two main types of triggers:

Allergens – such as dust mites, pollen, moulds, pets, or pests.
Irritants – such as smoke, vaping, pollution, strong odours, or chemical fumes.

For people with wheezing or asthma, exposure to allergens can increase the risk of symptoms or an asthma attack.

Understanding Allergen Triggers

Allergen triggers only affect people who are allergic to them. Your paediatric respiratory doctor can help identify your child’s triggers through testing, although you may already notice symptoms after certain exposures.

Symptoms may start straight away or develop hours later. Managing allergens is an important step in controlling asthma and preventing flare-ups.

If you are a parent or caregiver of a child or young person with asthma, teaching them how to avoid triggers is a key part of keeping their asthma under control.

House Dust Mites

Dust Mite - High magnification image of a dust mite

What is a house dust mite?

House dust mites are tiny creatures, about a quarter of a millimetre long. They do not live on humans, but close to us, feeding on the dead skin cells we shed. They thrive in warm, humid conditions and are commonly found in bedding, carpets, soft furnishings, and clothing. It is not possible to completely remove dust mites from your home, no matter how clean it is. However, reducing exposure can make a big difference for children with asthma and allergies.

Why do dust mites cause allergy symptoms?

It is not the mite itself, but proteins in their droppings that cause symptoms. Each mite produces around 20 droppings daily, and these can remain allergenic even after the mite has died.

Symptoms of house dust mite allergy

House dust mite allergy is very common and is linked to asthma, eczema, and chronic (year-round) allergic rhinitis. Symptoms may include:

Sneezing, runny or blocked nose
Itchy nose, throat, or mouth
Postnasal drip and cough
Red, itchy, or watery eyes
Fatigue
Worsening eczema or asthma symptoms

Symptoms may be worse after sleeping in an infested bed, after housework, or in damp, older houses.

Treatments for dust mite allergy

Mild to moderate symptoms: nasal douching, non-sedating antihistamines, or intranasal antihistamine sprays
More severe symptoms: inhaled corticosteroids or combined steroid/antihistamine sprays
Persistent symptoms: speak to your doctor, as other treatments are available

Reducing exposure to dust mites

Because most exposure happens in the bedroom, start there:

Use allergen-proof covers on mattresses, duvets, and pillows
Wash bedding weekly at 60°C or higher
Remove carpets from bedrooms if possible
Vacuum floors and upholstery regularly with a HEPA-filter vacuum
Damp-wipe surfaces weekly
Wash or freeze stuffed toys regularly
Reduce humidity to below 50% using ventilation or dehumidifiers

Elsewhere in the home and beyond:

Use washable flooring or sealed surfaces instead of carpets on concrete floors.
Wash or replace curtains with light, washable fabrics.
Steam-clean carpets or use acaricide sprays carefully.
Keep cars clean and ventilated, as mites can live in car seats and vents.
Ensure good ventilation at work; use purifiers if needed.

Other Common Allergens

Moulds

Mould thrives in damp or humid environments
Wash visible mould from hard surfaces with soap and water
Please fix the water leaks as soon as possible
Keep humidity below 50% using air conditioning or a dehumidifier
Change air-conditioning filters monthly
Watch outdoor mould counts; stay indoors or wear a mask when counts are high
Avoid raking leaves, uncut fields, or working with hay

Pollens

Pollen comes from trees, weeds, and grasses
Check pollen counts and limit outdoor activity when counts are high
Stay indoors during mid-day and afternoon when pollen counts peak
Wear a mask for outdoor activities like gardening or mowing
Shower and wash hair after being outdoors; change clothes promptly
Keep windows closed in homes and cars; use air conditioning on “recirculate”
Don’t dry clothes outdoors during pollen season
Clean pets’ fur after walks to reduce pollen brought inside

Pests (Cockroaches and Rodents)

Store food in airtight containers
Take out rubbish daily and keep bins covered
Clean kitchens promptly; keep surfaces clutter-free
Avoid storing cardboard, paper bags, or newspapers indoors
Use traps or baits; fix leaks and seal cracks
If using sprays, ventilate well and keep the person with asthma out of the room for several hours

Animals (Pets with Fur or Feathers)

Allergies are caused by proteins in saliva, urine, and skin flakes
Keep pets out of bedrooms and sleeping areas
Keep pets off upholstered furniture and carpets
Wash pets weekly with warm water and soap
Use HEPA air filters and change them monthly

Action Steps

You can reduce asthma problems by:

Knowing and avoiding your child’s triggers as much as possible.
Talking to your doctor about management options.
Treating nasal allergy symptoms as well as asthma.
Taking asthma medicines exactly as prescribed and following your asthma action plan.
Keeping regular follow-up appointments with your asthma specialist and GP.

Request a referral or book an appointment with Professor Gupta today.

Based in London | Expert Paediatric Respiratory Care